1. Field of the Invention
The present invention relates generally to devices coupled to a network or system, and, in particular, to generating an identifier conforming to, for example, a World-Wide Name (“WWN”) format for such network or system.
2. Description of the Related Art
In a computer hardware system, a host controller connects a host system (the computer) to other devices via a peripheral bus. For example, a Small Computer System Interface (“SCSI”) host controller connects a SCSI disk to a computer via a SCSI peripheral bus. The host controller communicates between the SCSI bus and the host computer's internal bus, typically by issuing commands to the devices attached to the SCSI bus.
In a computer system with multiple peripheral devices, each attached device generally requires a unique identifier. Certain device interface technologies support such a unique identifier. For example, a Serial Attached SCSI (“SAS”) device has a globally unique identifier, called a World-Wide Name (“WWN”), assigned by the device manufacturer. The WWN uniquely identifies each SAS device attached to an array network in a manner similar to a MAC address uniquely identifying an Ethernet device on an Ethernet network.
Each WWN is an 8-byte number derived from a 3-byte Organizationally Unique Identifier (“OUI”) that is obtained from the Institute of Electrical and Electronics Engineers (“IEEE”) Registration Authority. The OUI is subsequently used by a vendor or manufacturer to uniquely identify itself. Further, using the other five bytes of the WWN allows the manufacturer to assign a globally unique identifier to a particular piece of equipment. All SAS devices are programmed with a WWN. The WWN is reported to the host system on page 83 of the SCSI Inquiry command.
Serial Advanced Technology Attachment (“SATA”) devices can generally be used interchangeably with SAS devices. SATA devices generally offer slower data transfer rates than SAS devices, but, due to their lower cost, SATA devices are prevalent in many systems. Many, but not all, SATA devices also have a WWN assigned by the device manufacturer. SATA devices that do not support a WWN might not exhibit reliable performance in computer systems that require a WWN because such devices cannot be uniquely identified and configured by the computer system.
However, SATA devices are programmed with an ASCII identification string. The ASCII identification string is reported to the host system on page 83 of the SCSI Inquiry command. The ASCII identification string is assigned by the manufacturer and is unique for each disk. The ASCII identification string includes a vendor ID, a disk type ID and a disk serial number. However, this ASCII identification string is not in a format that is compatible with the WWN, and thus cannot be used to create a unique identifier.